From students with love: new bacteria named after an Indian microbiologist

Lekha Bandopadhyay

Researchers from North Bengal University, Siliguri, Bose Institute, Kolkata, and Kalyani University, Kalyani, have identified a new genus of bacteria which can degrade a potent neurotoxin that has been responsible for several food-poisoning outbreaks. The researchers have named the new isolate Pradoshia eiseniae, as a tribute to their mentor, the late Indian microbiologist Pradosh Roy.

Electron micrograph of Prodoshia eiseniae&#x3B; Inset: Pradosh Roy
Electron micrograph of Prodoshia eiseniae; Inset: Pradosh Roy  (Photo: Ranadhir Chakraborty and Wriddhiman Ghosh)

Led by Ranadhir Chakraborty, Professor, North Bengal University, Siliguri, a group of researchers have identified a new genus of bacteria capable of degrading a fatal neurotoxin, 3‑nitropropionic acid (3‑NPA), produced by many plants and fungi. The scientists named the new bacteria Pradoshia eiseniae, to honor their beloved mentor late Pradosh Roy, an eminent Indian microbiologist.

Pradoshda is omnipresent in our mindscape. He pops up every now and then in our daily discourse,” reflect Chakraborty and Wriddhiman Ghosh, Associate Professor at Bose Institute, Kolkata. Chakraborty and Ghosh, who collaborated for this study, were incidentally the first and last PhD scholars to finish their thesis under Roy’s supervision, respectively.

Roy worked at the Department of Microbiology of Bose Institute from 1990 till his untimely death from cancer in 2005. In his short lifespan, he made pioneering contributions in the discovery of genes and regulatory elements essential for microbial sulfur oxidation. His contemporary Arun Lahiri Majumder, presently an INSA Senior Scientist, describes Roy as An extremely brilliant and innovative scientist, he interacted with his students like friends. They learned from each other. He was loved by his students and colleagues alike because of his remarkable unassuming nature.”

The hunt in the worm gut

Capable of crossing the blood brain barrier, 3‑NPA irreversibly inhibits mitochondrial respiration causing involuntary muscle contraction. There are several reports of food poisoning outbreaks caused by this neurotoxin. Interestingly, some cattle can convert it to nontoxic forms with a little help from their ruminal microbes. So what about earthworms, who are famous for being voracious dung eaters and consuming rotting vegetation on the ground, both being potential sources of 3‑NPA?

If you notice those worms, they rarely appear sickly, suggesting a very strong immune system,” says Chakraborty. As these worms obviously have the guts to deal with toxic compounds like 3‑NPA, researchers of the current study aimed to test whether any assistance was coming from the microbial community within the worm gut.

The researchers cultured the gut content of redworm Eisenia fetida on laboratory media containing 3‑NPA. From this, they were able to isolate 3‑NPA consuming bacteria, even capable of surviving solely on a diet of this neurotoxin.

An all-round analysis of the isolate confirmed characteristics typical of spore forming members of the Bacillaceae family. However, there were enough differences from other known members of the family to demand that the new bacteria be classified into a separate genus and species. Decoding the bacterial genome sequence unveiled the presence of enzymes necessary to break 3‑NPA. The genus of this new Bacillaceae has been named Pradoshia after Roy and the species eiseniae after the source organism E. fetida.

P. eiseniae can be useful in several ways in the bioremediation of toxic 3‑NPA,” notes Chakraborty. Punyasloke Bhadury, who studies marine microbes, currently Head of the Department of Biological Sciences at Indian Institute of Science Education and Research, Kolkata, says, This is a potentially novel discovery with far-reaching consequences for safeguarding human health. This bacterium can offer a new approach in the food industry towards breakdown of 3‑NPA.”

A lasting imprint

Ghosh says, As our guide, Pradoshda was always thematic and philosophical, dealt with logic-building and seldom talked about the techniques, or for that matter the fashionable methods of contemporary science; and that’s exactly why he hasn’t lost, and shall never lose his relevance in our thought process and intellectual existence.” 

In this era of publishing madness, this inspiring mentor-mentee connection instead reminds us that there is more to the scientific enterprise. As Chakraborty recalls Roy often saying, Think differently!”

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